I have input file which is given below
Input file
10,9:11/61432568509 118,1:/20130810014023 46,440:4/GTEL 10,9:11/61432568509 118,1:/20130810014023 46,44
A short awk version
awk
awk 'ORS=NR%3?",":RS' file
Shortened, thanks to iiSaymour